"Social Facilitation" Is the Answer to Which Question

"Social facilitation" is the answer to which question?

A) What is the tendency for an individual to exert more effort in a group when he is held individually responsible for an outcome?
B) What is the likelihood that in a social situation people are more likely to help if there are few observers?
C) What is the tendency to exhibit your dominant response on a task when other people are present?
D) What is the tendency to look to the actions of others when making decisions about how to act in uncertain social situations?